For any development containing designated open space, the City Planning Commission may allow the amount of designated open space to be counted as lot area for bulk computations to exceed the amount permitted under Section 107-224.

As a condition for granting a permit for such modifications, the Commission shall find that:

(a)        that for the occupants of the site itself, the ill effects of concentration of buildings or accessory off-street parking are avoided or overcome by the manner in which the buildings are sited and yards and other open areas arranged; and

(b)        that the concentration of buildings or activities will not adversely affect any other zoning lot outside the development by restricting access of light and air, impairing privacy or creating traffic congestion.